Degree profiles of uniform polynomial consequences: Linear lower bounds for Nullstellensatz and Polynomial Calculus
Søren Riis
cs.CC
Nov 5, 2026 · v1
cs.LO math.LO
TL;DR
The linear NS/PC degree lower bounds, four-way classification and undecidability results are formalised in Lean 4.26.0 with Mathlib, released as a Zenodo archive.
Abstract
This paper proves asymptotically optimal linear degree lower bounds for Nullstellensatz and Polynomial Calculus, yielding a four-way polynomial-versus-exponential proof-size classification for uniform polynomial consequences over fields of positive characteristic. The size bounds use full, explicit coefficient lists, including zeros. Apart from a fixed finite initial range, exactly one of four cases occurs: $\mathrm T_1$, bounded degree; $\mathrm T_2$, degree at least linear in the universe size $n$; $\mathrm T_3$, constant degree on some residue classes and at least linear degree on the others; or $\mathrm T_4$, infinitely many recurring finite degrees, with bounded-degree subsequences and finite $Ω(n)$ peaks at arbitrarily large sizes. Thus the size patterns are polynomial bounds, exponential lower bounds, a periodic mixture, or polynomial subsequences with finite exponential peaks, respectively. Underivable targets have degree $\infty$, and both proof systems assign the same type. The result strengthens my 2008–2009 refutation classification and extends it to uniform consequences. The proof uses degree-preserving lifting with onset and period bounds linear in the degree. A common $p$-adic hardness spectrum describes the four types topologically. Distinguishing any two types is undecidable already for refutations. The linear degree bounds, four-way classification and pairwise undecidability results have been formalised and verified in Lean. The Lean formalisation, verification records and an accompanying tutorial are available in the supporting materials (
https://doi.org/10.5281/zenodo.23965838).
Problem
The question is how much degree Nullstellensatz and Polynomial Calculus proofs need to derive uniform polynomial consequences over fields of positive characteristic. Earlier work gave only logarithmic (NS) and double-logarithmic (PC) lower bounds, and covered only refutations.
Approach
The proof uses degree-preserving lifting via an exact label-deletion operation on permutation modules, built from nilpotent block operators and a common group-algebra projector. It gives periodicity in the universe size with onset and period linear in the degree. The construction handles characteristic two first, then odd characteristic, and uses rook-coordinate realisation of zero-marginal corrections. The core results are machine-checked in Lean with Mathlib.
Results
The paper proves asymptotically optimal linear degree lower bounds and a four-way classification (bounded, linear, periodic mixture, fluctuating with linear peaks), with the same type for NS and PC. Distinguishing any two types is undecidable already for refutations. The degree bounds, classification and undecidability endpoints are verified in Lean; the topological corollary is not.
| Type | Degree behaviour | Size consequence |
|---|
| T1 | Bounded degree | Polynomial upper bounds |
| T2 | Linear lower bounds | Exponential lower bounds |
| T3 | Constant on some residues, linear on others | Periodic mixture |
| T4 | Infinitely many recurring levels, finite linear peaks | Polynomial subsequences with exponential peaks |
Four degree profiles and size consequences